glSamplerParameter — set sampler parameters
void glSamplerParameterf(
|
GLuint sampler, |
| GLenum pname, | |
GLfloat param); |
void glSamplerParameteri(
|
GLuint sampler, |
| GLenum pname, | |
GLint param); |
void glSamplerParameterfv(
|
GLuint sampler, |
| GLenum pname, | |
const GLfloat * params); |
void glSamplerParameteriv(
|
GLuint sampler, |
| GLenum pname, | |
const GLint * params); |
void glSamplerParameterIiv(
|
GLuint sampler, |
| GLenum pname, | |
const GLint *params); |
void glSamplerParameterIuiv(
|
GLuint sampler, |
| GLenum pname, | |
const GLuint *params); |
sampler
Specifies the sampler object whose parameter to modify.
pname
Specifies the symbolic name of a single-valued sampler parameter.
pname can be one of the following:
GL_TEXTURE_WRAP_S,
GL_TEXTURE_WRAP_T,
GL_TEXTURE_WRAP_R,
GL_TEXTURE_MIN_FILTER,
GL_TEXTURE_MAG_FILTER,
GL_TEXTURE_MIN_LOD,
GL_TEXTURE_MAX_LOD,
GL_TEXTURE_COMPARE_MODE,
GL_TEXTURE_COMPARE_FUNC.
For the vector commands
(glSamplerParameter*v),
pname can also be
GL_TEXTURE_BORDER_COLOR.
param
For the scalar commands, specifies the value of
pname.
params
For the vector commands
(glSamplerParameter*v), specifies a
pointer to an array where the value or values of
pname are stored.
glSamplerParameter assigns the value or values in params to the sampler parameter
specified as pname.
sampler specifies the sampler object to be modified, and must be the name of a sampler object previously
returned from a call to glGenSamplers.
The following symbols are accepted in pname:
GL_TEXTURE_MIN_FILTER
The texture minifying function is used whenever the pixel being textured maps to an area greater than one texture element. There are six defined minifying functions. Two of them use the nearest one or nearest four texture elements to compute the texture value. The other four use mipmaps.
A mipmap is an ordered set of arrays representing the same image at progressively lower resolutions. If the texture has dimensions , there are mipmaps. The first mipmap is the original texture, with dimensions . Each subsequent mipmap has dimensions , where are the dimensions of the previous mipmap, until either or . At that point, subsequent mipmaps have dimension or until the final mipmap, which has dimension . To define the mipmaps, call glTexStorage2D, glTexImage2D, glTexStorage2D, glTexImage3D, or glCopyTexImage2D with the level argument indicating the order of the mipmaps. Level 0 is the original texture; level is the final mipmap.
params supplies a function for minifying the texture as one of the
following:
GL_NEAREST
Returns the value of the texture element that is nearest (in Manhattan distance) to the center of the pixel being textured.
GL_LINEAR
Returns the weighted average of the four texture elements that are closest to the center of the pixel being textured.
GL_NEAREST_MIPMAP_NEAREST
Chooses the mipmap that most closely matches the size of the pixel
being textured and uses the GL_NEAREST criterion
(the texture element nearest to the center of the pixel)
to produce a texture value.
GL_LINEAR_MIPMAP_NEAREST
Chooses the mipmap that most closely matches the size of the pixel
being textured and uses the GL_LINEAR criterion
(a weighted average of the four texture elements that are closest
to the center of the pixel)
to produce a texture value.
GL_NEAREST_MIPMAP_LINEAR
Chooses the two mipmaps that most closely match the size of the pixel
being textured and uses the GL_NEAREST criterion
(the texture element nearest to the center of the pixel)
to produce a texture value from each mipmap.
The final texture value is a weighted average of those two values.
GL_LINEAR_MIPMAP_LINEAR
Chooses the two mipmaps that most closely match the size of the pixel
being textured and uses the GL_LINEAR criterion
(a weighted average of the four texture elements that are closest
to the center of the pixel)
to produce a texture value from each mipmap.
The final texture value is a weighted average of those two values.
As more texture elements are sampled in the minification process,
fewer aliasing artifacts will be apparent.
While the GL_NEAREST and GL_LINEAR minification functions can be
faster than the other four,
they sample only one or four texture elements to determine the texture value
of the pixel being rendered and can produce moire patterns
or ragged transitions.
The initial value of GL_TEXTURE_MIN_FILTER is
GL_NEAREST_MIPMAP_LINEAR.
GL_TEXTURE_MAG_FILTER
The texture magnification function is used when the pixel being textured
maps to an area less than or equal to one texture element.
It sets the texture magnification function to either GL_NEAREST
or GL_LINEAR (see below). GL_NEAREST is generally faster
than GL_LINEAR,
but it can produce textured images with sharper edges
because the transition between texture elements is not as smooth.
The initial value of GL_TEXTURE_MAG_FILTER is GL_LINEAR.
GL_NEAREST
Returns the value of the texture element that is nearest (in Manhattan distance) to the center of the pixel being textured.
GL_LINEAR
Returns the weighted average of the four texture elements that are closest to the center of the pixel being textured.
GL_TEXTURE_MIN_LOD
Sets the minimum level-of-detail parameter. This floating-point value limits the selection of highest resolution mipmap (lowest mipmap level). The initial value is -1000.
GL_TEXTURE_MAX_LOD
Sets the maximum level-of-detail parameter. This floating-point value limits the selection of the lowest resolution mipmap (highest mipmap level). The initial value is 1000.
GL_TEXTURE_WRAP_S
Sets the wrap parameter for texture coordinate
to either GL_CLAMP_TO_EDGE, GL_MIRRORED_REPEAT, GL_REPEAT, or
GL_CLAMP_TO_BORDER.
GL_CLAMP_TO_EDGE causes
coordinates to be clamped to the
range
,
where
is the size
of the texture in the direction of clamping.
GL_REPEAT causes the
integer part of the
coordinate to be ignored; the GL uses only the
fractional part, thereby creating a repeating pattern.
GL_MIRRORED_REPEAT causes the
coordinate to be set to the
fractional part of the texture coordinate if the integer part of
is
even; if the integer part of
is odd, then the
texture coordinate is
set to
,
where
represents the fractional part of
.
GL_CLAMP_TO_BORDER evaluates coordinates in a similar manner to GL_CLAMP_TO_EDGE.
However, in cases where clamping would have occurred in GL_CLAMP_TO_EDGE mode, the fetched texel data
is substituted with the values specified by GL_TEXTURE_BORDER_COLOR.
Initially, GL_TEXTURE_WRAP_S is set to GL_REPEAT.
GL_TEXTURE_WRAP_T
Sets the wrap parameter for texture coordinate
to either GL_CLAMP_TO_EDGE, GL_MIRRORED_REPEAT, GL_REPEAT, or
GL_CLAMP_TO_BORDER. See the discussion under GL_TEXTURE_WRAP_S.
Initially, GL_TEXTURE_WRAP_T is set to GL_REPEAT.
GL_TEXTURE_WRAP_R
Sets the wrap parameter for texture coordinate
to either GL_CLAMP_TO_EDGE, GL_MIRRORED_REPEAT, GL_REPEAT, or
GL_CLAMP_TO_BORDER. See the discussion under GL_TEXTURE_WRAP_S.
Initially, GL_TEXTURE_WRAP_R is set to GL_REPEAT.
GL_TEXTURE_COMPARE_MODE
Specifies the texture comparison mode for currently bound textures.
That is, a texture whose base internal format is GL_DEPTH_COMPONENT or
GL_DEPTH_STENCIL; see
glTexImage2D)
Permissible values are:
GL_COMPARE_REF_TO_TEXTURE
Specifies that the interpolated and clamped
texture coordinate should
be compared to the value in the currently bound texture. See the
discussion of GL_TEXTURE_COMPARE_FUNC for details of how the comparison
is evaluated. The result of the comparison is assigned to the red channel.
GL_NONE
Specifies that the red channel should be assigned the appropriate value from the currently bound texture.
GL_TEXTURE_COMPARE_FUNC
Specifies the comparison operator used when GL_TEXTURE_COMPARE_MODE is
set to GL_COMPARE_REF_TO_TEXTURE. Permissible values are:
| Texture Comparison Function | Computed result |
|---|---|
GL_LEQUAL
|
|
GL_GEQUAL
|
|
GL_LESS
|
|
GL_GREATER
|
|
GL_EQUAL
|
|
GL_NOTEQUAL
|
|
GL_ALWAYS
|
|
GL_NEVER
|
where is the current interpolated texture coordinate, and is the texture value sampled from the currently bound texture. is assigned to .
GL_TEXTURE_BORDER_COLOR
The data in params specifies four values that define the border values that
should be used for border texels. If a texel is sampled from the border of the texture, the
values of GL_TEXTURE_BORDER_COLOR are interpreted as an RGBA color to match the
texture's internal format and substituted for the non-existent texel data. If the texture contains depth
components, the first component of GL_TEXTURE_BORDER_COLOR is interpreted as a depth value.
The initial value is
.
If the values for GL_TEXTURE_BORDER_COLOR are specified with glSamplerParameterIiv
or glSamplerParameterIuiv, the values are stored unmodified with an internal data type of
integer. If specified with glSamplerParameteriv, they are converted to floating point with the following
equation:
.
If specified with glSamplerParameterfv, they are stored unmodified as floating-point values.
If a sampler object is bound to a texture unit and that unit is used to sample from a texture, the parameters in the sampler are used to sample from the texture, rather than the equivalent parameters in the texture object bound to that unit. This introduces the possibility of sampling from the same texture object with different sets of sampler state, which may lead to a condition where a texture is incomplete with respect to one sampler object and not with respect to another. Thus, completeness can be considered a function of a sampler object and a texture object bound to a single texture unit, rather than a property of the texture object itself.
The results of a texture lookup are undefined if:
The sampler used in a texture lookup function is not one of the shadow sampler types, the texture object's base
internal format is GL_DEPTH_COMPONENT or GL_DEPTH_STENCIL, and the
GL_TEXTURE_COMPARE_MODE is not GL_NONE.
The sampler used in a texture lookup function is one of the shadow sampler types, the texture object's base internal format
is GL_DEPTH_COMPONENT or GL_DEPTH_STENCIL, and the
GL_TEXTURE_COMPARE_MODE is GL_NONE.
The sampler used in a texture lookup function is one of the shadow sampler types, and the texture object's base
internal format is not GL_DEPTH_COMPONENT or GL_DEPTH_STENCIL.
GL_INVALID_OPERATION is generated if sampler is not the name of a sampler object previously
returned from a call to glGenSamplers.
GL_INVALID_ENUM is generated if params should have a defined
constant value (based on the value of pname) and does not.
GL_INVALID_ENUM is generated if glSamplerParameter{if} is called for a non-scalar
parameter (pname GL_TEXTURE_BORDER_COLOR).
| OpenGL ES API Version | ||||
|---|---|---|---|---|
| Function Name | 2.0 | 3.0 | 3.1 | 3.2 |
glSamplerParameterf
|
- | ✔ | ✔ | ✔ |
glSamplerParameteri
|
- | ✔ | ✔ | ✔ |
glSamplerParameteriv
|
- | ✔ | ✔ | ✔ |
glSamplerParameterfv
|
- | ✔ | ✔ | ✔ |
glSamplerParameterIiv
|
- | - | - | ✔ |
glSamplerParameterIuiv
|
- | - | - | ✔ |
Copyright © 2010-2015 Khronos Group. This material may be distributed subject to the terms and conditions set forth in the Open Publication License, v 1.0, 8 June 1999. https://opencontent.org/openpub/.